Tuning the Electron Affinity and Secondary Electron Emission of Diamond (100) Surfaces by Diels−Alder Reaction

Abstract

The tuning of electron affinity and secondary electron emission on diamond (100) surfaces due to cycloaddition with 1,3-butadiene is investigated by photoemission experiments and density functional theory (DFT) calculations. A significant reduction in electron affinity up to 0.7 eV and enhancement of secondary electron emission were observed after 1,3-butadiene adsorption. The lowering of vacuum level via 1,3-butadiene adsorption is supported by DFT calculations. The C-H bonds in the covalently bonded organics on diamond contribute to the enhanced secondary electron emission and reduced electron affinity in a mechanism similar to that of C-H bonds on hydrogenated diamond surfaces. This combination of strong secondary emission and low electron affinity by the organic functionalization of diamond has potential applications in diamond-based molecular electronic devices.

Negative electron affinity of diamond and its application to high voltage vacuum power switches

“…This paper has been focused on the H‐terminated surfaces of diamond. Recently, other functionalized diamond surfaces were reported as stable NEA surfaces, such as a cycloaddition reaction of 1,3‐butadiene on the bare diamond surface , and a lithium coated O‐terminated diamond surface . The latter case in particular may be relevant to the vacuum power switch applications since it is robust in air and high temperatures.…”

Diamond PN/PIN Diode Type Electron Emitter with Negative Electron Affinity and Its Potential for the High Voltage Vacuum Power Switch

“…8.22 was also drawn by a green line. With assuming a system voltage of 100 kV, the open circle shifts toward to the right along with the green line, and then ξ reaches filled yellow star with over 90 %, even with the same electron emitter surfaces, such as a cycloaddition reaction of 1,3-butadiene on the bare diamond surface [72], and a lithium coated O-terminated diamond surface [73].…”

Spatial Effect of CH Dipoles on the Electron Affinity of Diamond (100)‐2×1 Adsorbed with Organic Molecules

“…These calculated values, which show that the hydrogenated surface has NEA, and the clean surface has PEA, are in good agreement with other theoretical and experimental studies. [13,21] 2.3. Hydrocarbon Adsorption on C-2 1 Surfaces…”

“…The optimized configuration of 1,3-butadiene at 25 % coverage has the molecular plane of the 6-membered ring nearly parallel to the surface normal, which agrees with previous reports by Qi and coworkers. [13] When the coverage of 1,3-butadiene is increased to 50 %, the repulsive interactions between hydrogen atoms of neighbouring adsorbates cause the binding energies to be endothermic when considering adsorption onto two adjacent surface dimers. To avoid steric repulsion, 1,3-butadiene has to be adsorbed on diagonally facing dimers in the 4 2 unit cell, as shown in Figure 3b.…”

“…Indeed, we have previously observed the lowering of electron affinities on CA C H T U N G T R E N N U N G (100) 2 1 following hydrocarbon adsorption. [12,13] Several factors, such as the coverage of these hydrocarbons on diamond, as well as the geometrical orientation of the CÀH dipoles on these adsorbed species, may produce different effects on the surface electronic properties of the diamond. In order to investigate the roles of these factors, we carry out sticking probability studies to assess the reactivity of the clean diamond surface towards allyl organics such as acetylene and butadiene.…”